Multi-objective aerodynamic shape optimization for unsteady viscous flows

This paper presents an adjoint method for the multi-objective aerodynamic shape optimization of unsteady viscous flows. The goal is to introduce a Mach number variation into the Non-Linear Frequency Domain (NLFD) method and implement a novel approach to present a time-varying cost function through a multi-objective adjoint boundary condition. The paper presents the complete formulation of the time dependent optimal design problem. The approach is firstly demonstrated for the redesign of a helicopter rotor blade in two-dimensional flow and in three-dimensional viscous flow, the technique is employed to validate and redesign the NASA Rectangular Supercritical Wing (RSW).     

Experimental investigations on the SiO<Subscript>2</Subscript> flux-assisted GTA welding of super-austenitic stainless steels

Analyzed in this paper are barrier properties of wood specimens treated by ball burnishing. For the purpose of experimental investigation, special device was designed which allows continuous monitoring of the volume of water absorbed by specimen within particular time intervals. The device allows water pressurized at 3 bar to efficiently penetrate specimen internal structure over its burnished/non-burnished surface interface. The experimental investigation encompassed six types of wood—beech, acacia, walnut, oak, linden, and ash tree. Comparative analysis was performed to establish relative resistance to water penetration in burnished and non-burnished specimens, as well as the quantities of water volume absorbed over time. The results indicate that ball burnishing is capable of enhancing barrier properties in all of the examined types of wood.     

Management,conversion, and utilization of waste plastic as a source of sustainable energy to run automotive: a review

Increased usage of plastic and absence of an efficient system to address its non-degradability has become a serious issue threatening the human life. On the other hand, increased fossil fuel consumption which led to their depletion necessitates the search for an alternative that could replace the conventional fuels and alongside abate the emissions. Both the non-degradability of plastic and need for an alternative fuel can be addressed by converting the waste plastic to useful energy. The present article reviews about pyrolysis, a chemical treatment to convert waste plastic to energy. It also focuses on its functional feasibility as a fuel in a compression ignition engine. Reportedly, waste plastic oil when used in a diesel engine yields lesser thermal efficiency, higher brake specific fuel consumption, increased emissions of carbon monoxides, and oxides of nitrogen and unburnt hydrocarbons. Irrespective of its disadvantages, it is worthwhile to note that it is waste plastic which is converted to useful energy. However, not much work on the technical feasibility and functional efficacy of waste plastic oil as a fuel in a diesel engine is reported, and hence, research in this application seems to gain its focus in near future.     

Preparation and Characterization Studies of Nanostructured CdO Thin Films by SILAR Method for Photocatalytic Applications

This work reports the preparation of cadmium oxide (CdO) thin films with different molar concentrations on glass substrate by simple and low cost SILAR (Successive Ionic Layer Adsorption and Reaction) method. The characterization, XRD pattern confirmed the presence of polycrystalline CdO in the deposited thin films with the cubic structure. The surface morphology and elemental composition of prepared thin films have been examined by scanning electron microscopy equipped with energy dispersive X-ray (EDX) analysis system. The optical property of the films was analyzed by UV–visible spectroscopy. The band gap of the deposited thin films was estimated by Tauc’s plot and it was found to be 2.6–2.8 eV. The prepared thin films were examined for the decomposition of the Methylene Blue (MB) dye which was visualized by UV-Visible spectroscopy, by decreasing the intensity of absorbance and concentration.     

NUMERICAL AERODYNAMIC SIMULATION OF STEADY AND TRANSIENT FLOWS AROUND TWO-DIMENSIONAL BLUFF BODIES USING THE NONSTAGGERED GRID SYSTEM

The time-averaged Navier-Stokes equations are solved numerically by a finite-volume method and applied to study flow around two-dimensional bluff bodies. The finite-volume equations are formulated in strong conservative form on a general, nonorthogonal grid system. The resulting equations are then solved by an implicit, time marching, pressure-correction based algorithm. If the flow problem has a steady state solution, then it is obtained by taking sufficient time steps until Ike flow field remains unchanged with time. As test cases for the developed methodology, two problems are selected; one has a steady state solution and the other has only a transient solution. Numerical predictions are obtained with the standard k-? turbulence model for the steady state, turbulent flow problem. The k-? model was able to predict the major, experimentally observed flow characteristics including the small separation bubble near the rear end of the body selected for the steady state test case. For the transient test case, the algorithm correctly captured the transient nature of the problem. However, agreement with the experimental results was only moderate because of the lower order differencing scheme employed in the method.     

Pentathiepins: A Novel Class of Glutathione Peroxidase 1 Inhibitors that Induce Oxidative Stress,Loss of Mitochondrial Membrane Potential and Apoptosis in Human Cancer Cells

A novel class of glutathione peroxidase 1 (GPx1) inhibitors, namely tri- and tetracyclic pentathiepins, has been identified that is approximately 15 times more potent than the most active known GPx1 inhibitor, mercaptosuccinic acid. Enzyme kinetic studies with bovine erythrocyte GPx1 indicate that pentathiepins reversibly inhibit oxidation of the substrate glutathione (GSH). Moreover, no inhibition of superoxide dismutase, catalase, thioredoxin reductase or glutathione reductase was observed at concentrations that effectively inhibit GPx1. As well as potent enzyme inhibitory activity, the pentathiepins show strong anticancer activity in various human cancer cell lines, with IC₅₀ values in a low-micromolar range. A representative tetracyclic pentathiepin causes the formation of reactive oxygen species in these cells, the fragmentation of nuclear DNA and induces apoptosis via the intrinsic pathway. Moreover, this pentathiepin leads to a rapid and strong loss of mitochondrial membrane potential in treated cancer cells. On the other hand, evidence for the induction of ferroptosis as a form of cell death was negative. These new findings show that pentathiepins possess interesting biological activities beyond those originally ascribed to these compounds.     

Study of the Structural,Optical, Dielectric and Magnetic Properties of Copper-Doped SnO2 Nanoparticles

Journal of Electronic Materials - This work explores the structural, optical and dielectric properties and the magnetic behaviour of copper (Cu) (0–4%)-doped tin dioxide (SnO2) nanoparticles,...     

Engineering III–V Semiconductor Nanowires for Device Applications

III–V semiconductor nanowires offer potential new device applications because of the unique properties associated with their 1D geometry and the ability to create quantum wells and other heterostructures with a radial and an axial geometry. Here, an overview of challenges in the bottom-up approaches for nanowire synthesis using catalyst and catalyst-free methods and the growth of axial and radial heterostructures is given. The work on nanowire devices such as lasers, light emitting nanowires, and solar cells and an overview of the top-down approaches for water splitting technologies is reviewed. The authors conclude with an analysis of the research field and the future research directions.